DOVER — Lawyers for Seth Mazzaglia — charged with strangling University of New Hampshire sophomore Elizabeth "Lizzi" Marriott — launched his defense Monday with testimony from an investigator for the New Hampshire Public Defender’s office and a medical examiner from Connecticut.Through his cross-examination, prosecutor Peter Hinckley suggested that the investigator’s notes and reports were incomplete, one-sided and untimely. When the medical examiner was cross-examined by Assistant Attorney General Geoff Ward, he said he has seen one strangling case during his 29-year career and confirmed he’s being paid $4,000 a day for his testimony.On the witness stand Monday morning was the public defender’s investigator, Lisa Greenwaldt, who said she interviewed Mazzaglia’s ex-girlfriend and jailed co-defendant, Kathryn "Kat" McDonough, on Oct. 13, 2012 — four days after Marriott’s death. She said the interview was 3½ hours long and she was the only one who took notes.Prosecutors say Mazzaglia raped and strangled Marriott, 19, of Westborough, Massachusetts and then dumped her body in the Piscataqua River. Her body has never been found. The defense argues that McDonough actually killed Marriott during rough sex. Greenwaldt said McDonough initially claimed she was taking photos in a cemetery the night Marriott died, after Marriott failed to keep plans for a meeting they had. McDonough then changed her story to say she was with Mazzaglia "all night" and that Marriott died during consensual sex, Greenwaldt said."She was calm, she was very fluid in speaking with us, she was reflective and she was eager to help," Greenwaldt said.The investigator testified that she prepared a written report that she described as "a factual representation of what she told us happened that night." Greenwaldt said McDonough also provided "a lot of information" about bondage sex, but she did not include that in her report because it wasn’t pertinent to the investigation.On Oct. 17, 2012, McDonough was video recorded at the public defender’s office while she reviewed a written statement that was based on her oral interview two days earlier, Greenwaldt said. Because McDonough had "incriminated herself," the public defenders wanted to keep a record of it, she said.That video was previously played for the jury and showed McDonough occasionally giggling, grinning and yawning while describing the circumstances surrounding Marriott’s death. The video also showed McDonough demonstrating how she crouched down to sit on Marriott’s face before, she said, Marriott died during consensual sex while bound by ropes. McDonough has since recanted that story as a lie.During his cross-examination, Hinckley prompted Greenwaldt to admit that, during an unrecorded interview, McDonough drew a picture of a rope "harness" she said was put on Marriott before she died. Hinckley also projected a note written by Mazzaglia, outlining his version of events, while he asked Greenwaldt if McDonough had made the same specific admissions.In two dozen instances, Greenwaldt confirmed, Mazzaglia’s and McDonough’s stories differ.Greenwaldt also confirmed that she did not document what questions McDonough was asked during the initial interview and that the entire interview was not recorded. Hinckley noted that Greenwaldt’s notes document McDonough while talking about her family life, then immediately shift to her saying she was with Mazzaglia the night Marriott died, with no notes reflecting the context of the interview leading to that topic shift.The jury doesn’t get to see or hear what brought about that change of topic because it wasn’t documented in notes, or recorded, Hinckley said."I can’t apologize enough for that," Greenwaldt responded.Greenwaldt also confirmed writing a note in her report saying that, after McDonough said she had been in a cemetery, she was told by unnamed employees of the public defender’s office, "we think" something "of a more intimate nature" happened the night Marriott died. After that remark, McDonough then gave a story about a consensual sexual encounter, Hinckley said.The prosecutor prompted Greenwaldt to testify that her loyalty is to Mazzaglia’s defense and that her final written report from the initial interview was written this March, 18 months after it occurred.Hinckley also noted there was nothing in the investigator’s report to explain notations she’d made about a fetish website, "in control dominant," "master," "submissives," "queening" and "slaves.""She was explaining to me what some of the terms meant," Greenwaldt said.Hinckley said none of that was documented in her final report.Greenwaldt also confirmed there were no notes about McDonough’s mood or demeanor in her report, other than to say McDonough was reluctant to discuss witnesses Roberta Gerkin and Paul Hickock, who she later said helped dispose of Marriott’s body, then said that was a lie.On Monday afternoon, Mazzaglia’s defense team called Dr. Ira Kanfer, a forensic pathologist for the state of Connecticut, to the witness stand. Answering questions by defense attorney Joachim Barth, Kanfer was asked to discuss the physical differences seen in people who were strangled versus suffocated.Hinckley argues that Mazzaglia strangled Marriott from behind with a rope, raped her after she died, then plotted to get rid of her body and evidence. That’s the same story McDonough told when she was called to testify at trial, and previously to a grand jury, leading to an immunity deal and light prison sentence.Barth contends McDonough killed Marriott during consensual bondage sex by sitting on her face for 10 to 15 minutes while Marriott was bound with a rope "harness." McDonough previously told that story to Mazzaglia’s legal team, but now calls it a lie. She was convicted 11 months ago for helping Mazzaglia dispose of Marriott’s body off Peirce Island in Portsmouth and for witness tampering.Kanfer testified that he read McDonough’s grand jury testimony about Mazzaglia strangling Marriott for 10 to 15 minutes and said he didn’t believe most people could inflict that kind of pressure for that prolonged time. He said he also read Hickok’s grand jury testimony, which said he saw a red line around Marriott’s neck where plastic bags were tied "tightly." Kanfer said that based on those reports and that Marriott’s face was described as red and swollen, he believes she was suffocated, not strangled.Kanfer’s testimony contradicted that of Dr. Jennie Duval, chief medical examiner for the state of New Hampshire, who last week said observations of Marriott’s body, by laypeople who saw her after she died, indicate she did not die by smothering and that the observations are consistent with strangulation. Duval said bags placed on Marriott’s head would not leave a red mark around her neck because she was reportedly deceased at the time and her heart was no longer pumping blood.On cross-examination by Ward, Kanfer said he saw a drawing made by McDonough of the rope harness she said was placed on Marriott during consensual bondage sex and acknowledged it showed the rope around a neck, torso and legs, but not arms or wrists. He also confirmed that if someone was being smothered and their arms and hands were free, they would be expected to fight back.Kanfer was paid $4,000 a day for his previous deposition and for appearing at trial Monday, he confirmed.Mazzaglia is charged with two "alternate theory" counts of first-degree murder, one count of second-degree murder, two counts of hindering apprehension for murder, witness tampering, falsifying physical evidence and solicitation of escape.McDonough is serving 1½ to three years in prison in exchange for cooperating with authorities and offering testimony during Mazzaglia’s trial.Marriott’s phone last pinged at Mazzaglia’s Dover apartment, court records state. Her body was never found in spite of land and water searches by multiple agencies.